ABB Relion 670 series - Meshed Network Without Parallel Line

9.1.3.1 Meshed network without parallel line
The following fault calculations have to be done for three-phase, single-phase-to-ground
and two-phase-to-ground faults. With reference to Figure 251, apply a fault in B and then
calculate the current through-fault phase current I
fB
. The calculation should be done using
the minimum source impedance values for Z
A
and the maximum source impedance values
for Z
B
in order to get the maximum through fault current from A to B.
~ ~
Z
A
Z
B
Z
L
A B
IED
I
fB
Fault
ANSI09000022-1-en.vsd
ANSI09000022 V1 EN
Figure 251: Through fault current from A to B: I
fB
Then a fault in A has to be applied and the through fault current I
fA
has to be calculated,
Figure 252. In order to get the maximum through fault current, the minimum value for Z
B
and the maximum value for Z
A
have to be considered.
ANSI09000023-1-en.vsd
~ ~
Z
A
Z
B
Z
L
A B
IED
I
fA
Fault
ANSI09000023 V1 EN
Figure 252: Through fault current from B to A: I
fA
The IED must not trip for any of the two through-fault currents. Hence the minimum
theoretical current setting (Imin) will be:
1MRK 506 369-UUS - Section 9
Current protection
Line distance protection REL670 2.2 ANSI 489
Application manual